Phase shifting system



Aug. 17, 1965 c. J. PASQUIER ETAL 3,201,700

PHASE SHIFTING SYSTEM Filed may 1o, 1961 2 sheets-sheet 1 Aug; 17, 1965 c. J. PASQUIER ETAL 3,201,700

PHASE SHIFTING SYSTEM Filed May 10, 1961 2 Sheets-Sheet 2 k b n i l LL b n O Q LS LL; N v

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e? ai m 2 l o DO EQ2 OO s z S S' INI/mrow. cm1/af J. pAsQc//ER g BY .Jai/N C. GRAE/vf@ Y f ATTORNEY United States Patent O 3,261,799 PHASE Sit-lilirsibl@ SYSTEM Claude I. Pasquier, New Yorlr, NY., and .lohn C. Grashner, Glen Rock, NJ., assgnors to international 'Eelsphone and Telegraph Corporation, intiem NJ., a corporation of lf'aryland Filed May 1t?, 196i, Ser. No. 169,159 7 lairns. (Cl. 323-55) rl`his invention relates to a system for shifting the phase of a signal and more particularly to means for shifting the phase of a signal in discrete increments at a desired rate.

ln certain systems, such as loran, it is necessary to synchronize a master signal to a received signal of the same frequency. ln the receiver and associated equipment, the phase of the master signal is shifted until it is equal in phase to the received signal. The phase shifting is accomplished generally by electromechanical means, such as a resolver. There are, however, certain limitations attached to electromechanical means, such as a motor driven resolver; the rate of phase shift is limited as is also the range of the speed of phase shifting, and in cases where there is a fast drift, the mechanical limitations of a resolver prevent a fast phase correction.

It is an object of this invention to provide a phase shifting system that is `suitable for fast as well as slow drift of a signal.

it is another object to provide a phase shift system that will provide a continuous sequential phase shift to change the frequency of a signal very slightly.

In this invention, a sequential combination of in phase and quadrature components of a continuous wave produces phase rotation of a sine wave in 90 degree steps. Subsequent frequency division results in a controllable quency shift of the resulting wave by discrete phase steps. A feature of this invention is that first and second phase differing modulating signals are derived from the output of a signal generator. A given signal which is to be phase shifted is separately modulated with the first and second modulating signals and the outputs of the modulating means are then combined to produce the given signal phase shifted at a rate lthat is proportional to the frequency of the output of the sinal generator.

Another feature is that the signal generator is a relaxation oscillator and the pulse output thereof drives a binary circuit and frequency divider to produce two square wave modulating signals in quadrature rel-ation. The given signal and one of the square wave modulating signals is fed to 4a iirst balanced modulator and the given signal with a phase shift of 9() degrees is fed .to a second balanced modulator to which is also coupled the second modulating square wave signal. The outputs of the two nodulators are then combined and the resulting signal is the given signal which has been phase shifted in discrete steps at a rate that is proportional to the frequency of the relaxation oscillator.

The above-mentioned and other features and lobjects of this invention will become more lapparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIGURE l is a block diagram or the embodiment of this invention; and

FGURE 2 is a graph of waveforms useful in describing the operation of this invention together with a vectorial explanation of the phase shift ofthe signals.

Referring now to FIGURE l which is the block diagram of the embodiment of this invention, there is shown a relaxation oscillator l, the output of which are sharp pulses as shown at 2. The frequency of the oscillator as shown here can be varied in any conventional manner in three steps, as shown by the switch arrangement 3, having three vran u rice positions, slow, medium and fast, denoted respectively by the letters S, M and F. The output ofthe relaxation oscillator i. is fed to a bistable multivibrator 4 which has two outputs, one from each state, of square waves S and 6 which are 180 degrees out of phase with each other. The square wave output 5 is fed to a bistable multivibrator 7 and the square wave output 6 of the bistable multivibrator i is fed to 'a bistable multivibrator il. Multivibrators 7 and Sare turned on and oil in response to the positive going edges of the square waves 5 and 6, respectively from multivibrator 4, or, alternatively, both in response to the negative going edges of square waves S and o. A switching reset arrangement 9 capacitively couples, the bistable multivibrator 7 to .the bistable multivibrator d. With respect to PEG. l there are shown outputs from multivibrator rl Z1 and Z2 which are, respectively, square waves 5 and o. The square wave outputs of multivibrator 7 are respectively Z1 which is shown as waveform ZA and Z2 which is 180 out of phase with Z1 (multivibrator The arrowhead at the end of the line labelled Z2 from multivibrator '7 indicates that the Z2 output is fed to the reset switch. As may be desired this Z2 wave is coupled to the multivibrator 8 through either the left or right position of the reset switch. This :switch reset arrangement permits the direction of the drift of the relaxation oscillator to proceed in a forward or backward direction, either advancing or retarding the rate of change of the phase shift as may be desired, or may be left in the neutral position between the left and right contacts of the reset switch when the desired phase relationship has been established. The output lof the bistable multivibrator 7 is a square wave as shown in FIGURE 2A. The output of the bistable multivibrator 8 is also a square wave as shown in waveform ZB, which is offset from waveform 2A by 90 degrees. The outputs of the multivibrators 7 and S are coupled to impedance matching emitter followers 5l and lil. The output of the emitter follower 9 is coupled to balanced modulator il to which is also coupled a given continuous wave signal i2.. The output of the emitter follower l@ is coupled to `a balanced modulator .i3 to which is coupled also the given signal l2 after it has been phase shifted 90 degrees in the phase shifter ld. The outputs of balanced modulators il and i3 are combined at l5 to form a single output which is the continuous wave signal i2 phase shifted by an amount determined by the quadrature relationships of multivibrators 7 and 8 and at a rate which is proportional to the frequency of the relaxation oscillator. The combined output is then coupled to a divider lo to reduce the given continuous wave signal to a signal of the required frequency as may be desired.

The relaxation oscillator ll generates frequencies that are four times the desired drift rate, or rate of phase shift as determined by .the sweep speed selector 3. When the desired phase shift has been attained, the output of the relaxation oscillator l is stopped by means not shown but which are familiar to those skilled in the art. During the drift, `the oscillator l output as shown is fed to the rst multivibrator 4 which drives the multivibrators 7 and il in quadrature. That is, the driving multivibrator 7 is driven by the positive output from one transistor or tube, as the case may be, of the multivibrator d and the other driving multivibrator is driven by the positive output from the second tube or transistor of .the first multivibrator. rIhe square waves outputs of the multivibrators i and Si, 2A and 2B, cause the output of each modulator il and i3 to shift 180 degrees at the low frequency rate of the relaxation oscillator. Adding the output of the two modulators will give a sine wave output that continuously shifts phase in 9() degree steps. rifo control the direction of drift, the driving multivibrators 7 and S must run in'a particular quadrature relationship which is established by the reset connection switch 9. When the relexation oscillator is stopped, the output lof the modulator remains at the last established relationship. The frequency at which the outputs of modulators 1i and 13', el and e2, changes controls :the drift rate.V For example, for 600 Vmicrosec-onds/minute which is a slow drift, the phase of a 1GO kilocyclejs sine wave signal Vhas to be shifted 360 degrees a second or elrand e2 are changed at one c.p.s. For a fast drift, e1 and 2 are changed at SO c.p.s. and for a medium drift, el andez are changed at 50 c.p.s.

The vectorial relationship that exists between the outputs of the modulators 11 and 13 and the summation of these outputs at 15 is shown in FIGURE 2 in relation to the modulating square waves 2A and 2B. As stated above, the phase of the continuous wave signal is changed at the desired drift rate by combining two quadrature continuous wave signals which are alternately shifted 180 degrees in phase with a resulting continuous wave signal that is continuously phase shifted in 90 degree steps. Initially, e1 and e2 are in a quadrature relation shown in FIGURE 2C. ,Then when e2 is shifted 180 degrees the resultant, er,'rotates instantaneously froml 45 to 135 degrees, FIGURE 2D. Next, e1 is shifted 180 degrees and er moves from 135 degrees to 225 degrees, FIGURE 2E, andy then when ezis shifted 180 degrees, er moves from 225 degrees to 315 degrees, FIGURE 2F. Alternately, shifting e1 and e2 180 degrees results in the output continuously shifting phase Yin 90 degree steps. Since e1 and e2 are not shifted together, the output never goes through zero.Y v

In a reduction to practice of lthis system, the drift rates were setat Vl c.p.s., 50 c.p.s. and 500 c.p.s. The continuous wave signal was of the order of 100,00() c.p.s. By dividing down by ten the phase vshifted f` continuous wave signal er `in the divider 16, the resultant was a l()V kc. signal with phase shift steps of 9 degrees. This process of dividingdown can, of course, be continued so that the phase shift steps can be made as small as desired.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims. v

We claim: Y 1. ,A system to shift the phase of a signal in discrete increments comprising a relaxation oscillator, means to V2.. A system to shift the phase of a signal comprising a signal generator, means to derive first and second phase different modulating signals from the output of said signal generator, a given signal, means to modulate separately said given signal with said first and second modulating signals and means to combine the outputs of said modulating means to produce said given signal phase shifted at a rate that is proportional to the frequency of the output of said signal generator;

3. A system to shift the phase of a signal comprising` a source of pulse signals, means to generate from said pulse signals a first modulating'signal and a second modulating signal differing in phase from said first modulating signal, a continuous wave signal, means to modulate separately said continuous wave signal with said first and second modulating signals and means to combine the outputs of said modulating means to produce said continuous Wave signal phase shifted ata rate that is proportional to the frequency of said pulse signals.

4. A system to shift the phase of a signal in discrete increments comprising a source of pulse signals, means to generate from said pulse signals a first modulating square wave signal-and al second modulating square Wave signal that is in quadrature relation to said first modulating signal, a continuous wave signal, means to modulate separately said continuous wave signal with said first and second modulating signals, and means to combine the outputs of said modulating means to produce said continuousV wave signal phase vshifted at a rate that is proportional to the frequency of said pulse signals.

5. A system to shift the phase of aV signal in discrete increments comprising a relaxation oscillator, means to produce from the output of said relaxation oscillator two square waves 180 degrees out of phase with each other, first and second bistable multivibrators, means connecting one square Wave to said first multivibrator, means connecting the Vsecond square AWave to said second multivibrator, the outputs of said first and second multivibrators being square waves wherein the square wave output of said first multivibrator is in quadrature relation to the square wave output of said second multivibrator, a source of sine wave signals, first and second modulators, means coupling `the output of said first multivibrator and said sine wave signals to said first.

modulator, means coupling the output of said second multivibrator and said sine wave signals phase shifted .90 degreesto said second modulator, and means to combine the outputs of said first and second modulators, said comcontrol the frequency output of said relaxation oscillator, l

a first bistable multivibrator, means coupling the output ofsaid,Vv relaxation oscillator to said first bistable multivibrator to produce asthe two outputs thereof square waves lSQAdegreesout of phase with each other, second and'third bistable Ymultivibrators, means" connecting one voutputof said vfirst multivibrator to saidsecond multivibrator, means connecting the second output of said first multivibrator to said third multivibrator, the outputs of said second and third multivibrators being square ywaves wherein the square wave outputofysaid second multivibrator is in quadrature relation to the square wave outf put of said third multivibrator, means to control ythe quadrature relation of the outputs from said second and third multivibrators, a source of sine wave signals, first and second modulators, means coupling the output of said second multivibrator and said sine Wave signals to said first modulator, means coupling the output of said third multivibrator and said sine wave signals phase shifted 90 degrees to said second modulator, and means to combine the outputs of said first and second modulators, said combined output being the original sine wave signal phase shifted to discrete steps of 90 degrees, the rate of said phase shift being proportional to the frequency of the Y output of said relaxation oscillator and in a direction dependent upon said quadrature relation of the square wave outputs of said second and 1third Inultvibratnrs` bined output being the original sine wave signal phase shifted in discrete steps of 90 degrees, the rate of said phasel shift being proportional to the frequency output of said relexation oscillator.

6. VA system to shift Vthe phase of a signal in discrete increments comprising a relaxation oscillator, means to Y 'control the frequency output of said' relaxation oscillator,

means to produce from the output of said relaxation oscil- Vlator two square waves 180 degreesv out of phase with each other, first Aand second `bistable multivibrators,

means connecting onev square Wave to said first multivibrator, means connecting the second square wave to said second multivibrator, the outputsof said yfirst and second multivibrators being square waves wherein the square wave output of said first multivibrator is in kquad- Y rature relation to the square wave output of said second multivibrator, a source of sine Wavesignals, first and second modulators, means coupling the output of said first multivibrator and said sine wave signals to said first modulator, means coupling the output of said second multivibrator and said sine -wave signals phase shifted degrees to said second modulator, and means to combine the outputs of said first and second modulators, said combined output being the original sine wave signal phase shifted in discrete steps of 90 degrees, the rate of said phase shift being proportional to the frequency output of said relaxation' oscillator.

7 A system to shift the phase of a signal in discrete increments comprising a relaxation oscillator, means to control the frequency output of said relaxation oscillator, a first bistable multivibrator, means coupling the output of said relaxation oscillator to said first bistable multivibrator to produce as the two outputs thereof square Waves 180 degrees out of phase with each other, second and third bistable multivibrators, means connecting one output of said rst multivibrator to said second multivibrator, means connecting the second output of said rst multivibrator to said third multivibrator, the outputs of said second and third multivibrators being square Waves wherein the square wave output of said second multivibrator is in quadrature relation to the square wave output of said third multivibrator, a source of sine Wave signals, rst and second modulators, means coupling the output of said second multivibrator and said sine Wave signals to said rst modulator, means coupling the out- CII put of said third muitivibrator and said sine wave signals phase shifted 90 degrees to said second modulator, and means to combine the outputs of said first and second modulators, said combined output being the original sine Wave signal phase shifted in discrete steps of 90 degrees, the rate of said phase stift being proportional to the frequency of the output of said relaxation oscillator.

References Cited by the Examiner UNITED STATES PATENTS 2,635,226 4/53 Harris 328-455 X 2,668,238 2/54 Frink 32E-155 X 2,697,816 12/54 Weaver 332-45 3,027,523 3/62 Wilcox 328-24 X ARTHUR GAUSS, Primary Examiner.

HERMANN KARL SAALBACH, Examiner. 

1. A SYSTEM TO SHIFT THE PHASE OF A SIGNAL IN DISCRETE INCREMENTS COMPRISING A RELAXATION OSCILLATOR, MEANS TO CONTROL THE FREQUENCY OUTPUT OF SAID RELAXATION OSCILLATOR, A FIRST BISTABLE MULTIVIBRATOR, MEANS COUPLING THE OUTPUT OF SAID RELAXATION OSCILLATOR TO SAID FIRST BISTABLE MULTIWAVES 180 DEGREES OUT OF PHASE WITH EACH OTHER, SECOND WAVES 180 DEGRERES OUT OF PHASE WITH EACH OTHER, SECOND AND THIRD BISTABLE MULTIVIBRATORS, MEANS CONNECTING ONE OUTPUT OF SAID FIRST MULTIVIBRATOR TO SAID SECOND MULTIVIBRATOR, MEANS CONNECTING THE SECOND OUTPUT OF SAID FIRST MULTIVIBRATOR TO SAID THIRD MULTIVIBRATOR, THE OUTPUTS OF SAID SECOND AND THIRD MULTIVIBRATORS BEING SQUARE WAVES WHEREIN THE SQUARE WAVE OUTPUT OF SAID SECOND MULTIVIBRATOR IS IN QUADRATURE RELATION TO THE SQUARE WAVE OUTPUT OF SAID THIRD MULTIVIBRATOR, MEANS TO CONTROL THE QUADRATURE RELATION OF THE OUTPUTS FROM SAID SECOND AND THIRD MULTIVIBRATORS, A SOURCE OF SINE WAVE SIGNALS, FIRST AND SECOND MODULATORS, MEANS COUPLING THE OUTPUT OF SAID SECOND MULTIVIBRATOR AND SAID SINE WAVE SIGNALS TO SAID FIRST MODULATOR, MEANS COUPLING THE OUTPUT OF SAID THIRD MULVIBRATOR AND SAID SINE WAVE SIGNALS PHASE SHIFTED 90 DEGREES TO SAID SECOND MODULATOR, AND MEANS TO COMBINE THE OUTPUTS OF SAID FIRST AND SECOND MODULATORS, SAID COMBINED OUTPUT BEING THE ORIGINAL SINE WAVE SIGNAL PHASE SHIFTED TO DISCRETE STESP OF 90 DEGREES, THE RATE OF SAID PHASE SHIFT BEING PROPORTIONAL TO THE FREQUENCY OF THE OUTPUT OF SAID RELAXATION OSCILLATOR AND IN A DIRECTION DEPENDENT UPON SAID QUADRATURE RELATION OF THE SQUARE WAVE OUTPUTS OF SAID SECOND AND THIRD MULTIVIBRATORS. 